1. Field of the Invention
The present invention relates to a fiber unit used in a measurement probe that emits irradiation light to a sample and receives light from the sample.
2. Description of the Related Art
Conventionally, an optical measurement system has been known, which emits illumination light onto a sample such as a biological tissue and estimates characteristics of the sample on the basis of a measurement value of detected light reflected or scattered by the sample. Such an optical measurement system is constituted using: a light source emitting illumination light to a sample; an optical measurement apparatus having a detection unit detecting detected light from the sample; and a measurement probe, which is attachable to and detachable from the optical measurement apparatus, emits irradiation light to the sample, and receives light from the sample.
The measurement probe has a fiber unit including: an illumination fiber, one end of which is connected to a light source and the other end of which emits illumination light to a biological tissue; and a light receiving fiber, one end of which is connected to the detection unit and the other end of which receives light emitted from the biological tissue by emission from the emission fiber.
In such an optical measurement system, LEBS (low-coherence enhanced backscattering) for detecting characteristics of a biological tissue by: emitting, from an end of an illumination fiber of a measurement probe, low-coherence white light having a short spatial coherence length, to the biological tissue; and measuring intensity distributions of scattered light beams of different angles using a plurality of light receiving fibers.
Decrease in a diameter of the measurement probe is demanded in order to reduce burden placed on a patient upon insertion of the measurement probe inside the patient's body. For this demand, a diameter of each fiber of a fiber unit is required to be also decreased.
As a technique for decreasing the diameter of the fiber unit, Japanese Laid-open Patent Publication No. 5-341158 discloses a technique in which a receiving end portion of each fiber is bent to narrow a distance between the fibers, thereby decreasing the diameter, for example.